Protecting device for electric detonators



Aug 24 1926. 11,597,445

H. 1.. GRANT PROTECTING DEVICE FOR ELECTRIC DETONATORS Filed Oct. 19, 1925 flurry L. Gran/i9 atented Aug. 24,, .1926.

UNITED I. G, 01' TAMAQUA, PENNSYLVANIA. ASSIGNOR T0 ATLAS TOWDER COM- PAINY, 0F WILMINGTON, DELAWARE, A CORPORATION OF DELAWARE.

PROTECTING DEVICE FOR ELECTRIC DETONATORS.

Application filed. October This invention relates to a protecting device for electric detonators of. the character of that shown in my copending application, Serial No. 748,214, filed on Novemher 6, 1924. v

Like the device of the application referred to,-the protecting device of the present invention is intended to be applied to the lead in wires of electric detonators and to serve, while in position. to establish a short circuit between the two lead-in wires, so that any stray currents imposed upon the leadin wires, outwardly of the point of application of said device, may not find their way to the detonator and prematurely explode the same.

In the accompanying drawing:

Fig. 1 is a plan view of a detonator having the short circuiting clip of the present invention applied thereto.

Fig. 2 is an enlarged perspective view of the short circuiting clip. 7

Fig. 3 is a sectional view upon line 3+3 2 of Fig. 2 and Fig. 4 is a rlongitudinal sectional view through the clip, parallelism with one of the lead-in wires.

Like numerals designate corresponding parts in all of the figures of the drawing.

Referring to the drawing. 5 designates the conventional electric detonator and 6 and 7 designate'the usual lead-in wires of said detonator.

in the ordinary 'use of the detonator the flow of current of suflicient strength past an igniting element '8, which connects the inner ends of the wires 6 and 7 explodes the detonator. The lead-in wires are insulated, as indicated at 9 and 10. for. some distance from the detonator and the ends of the leadin wires are left bare beyond the point where the insulation terminates, to adapt them for ready' application tothe firing cable, leading from a blasting machine.

According to the present invention, a metallic clip of plate like form is bent upon itself and clipped into firm engagement with the lead-in wires, said clip lying adjacent the terminal ends of the insulation 9 and 10. Thus. the insulation protects the leadin wires from the point of application of theclip body 5 to the detonator and if any stray current be accidentally imposed upon the lead-in wires 6 and 7, outwardly of the 19, 1925. Serial No. 63,452.

point of application of the clip, the clip will serve as a short circuiting connection between said wires to prevent the passage of such current to point 8, and to prevent the creation of a difference of potential between the lead wires inwardly of the point of application of the clip.

- The clipmay be formed of any suitable material. though I prefer to employ aluminum. However, lead, tin, zinc, copper, brass upon the wires is assured.

The compression of the metal of the ribs 13 and 14. in the act of forming the grooves 11 and 12 and the crowding of the metal of the clip upon the lead-in wires. gives such density to the ribs 13 and 14 and such firm engagement of said ribs upon the wires 6 and 7. that when the clip is stripped longitudinally along the wires to the free ends thereof. a scraping effect is produced. which results in rendering the wires bright and clean and aids in efl'ecting a good electrical connection between said lead-in wires and the firing cable leading from the blasting machine.

The device of the present invention is of utility at all times between the time of manufacture of the detonator and the time when the same is. actually exploded on the job but it is of particular utility when the detonator is being transported and while it is being handled about the work preliminary to the actual firing of'a chargef.

It is not to be understood that the device is of utility only when actually touching the termination of the insulation. lit will give a very appreciable measure of protectioneven when spaced somewhat from the insulation because the influences which might bring about such difierence in potential between the lead wires as to explode the detonator. are not those sought to be created by an intelligent human agency but i only those which might accidentally occur. Stray currents of such low E. M. F. as to escape ordinary notice constitute a marked source of danger and. are rendered absolute- 6 1y harmless by this invention. The invention is not limited to the precise construction set forth but it' includes within its purview whatever changes ,fairly come within either the terms or the spirit 10 of the appended claims.

Having described my invention, claim is:

1. The combination with an electric .detonator and its bifilar lead-in wires, having what I the outer free and bared ends of a clip comprising a piece of sheet metal. ben't transversely across and electrically uniting said lead-in wires and capable of being stripped longitudinally therefrom.

2. The combination with an electric detonator and its bifilar lead-in wires, having the inner insulated portions and the outer free and bared ends, of a sheet metal clip of plate form bent about said wires, close 2 *enough to the point of termination of the insulation thereon, to practically prevent the creation of a difference of potential between the wires, between the point of application of the clip and the insulation.

3. The combination with an electric detonator and its bifilar lead-in wires having the outer free and bared ends, of a sheet metal clip, clipped thereon and having a rib indented therein into forciblev engagement with the wires of the detonator.

4. The combination with a detonator and its bifilar lead-in wires having the outer free and bared ends, of a metallic" clip thereabout and electrically uniting said lead-in wires and a plurality of ribs indented in the metal of the clip, and into forcible engagement with the said lead-in wires.

5. The combination with an electric detonator and its bifilar lead-in wires, having insulation extending from the detonator through a portion of the length of the leadin wires, the ends of the lead-in wires beyond said insulation being left bare and a metallic clip of plate form, bent transversely about said wires and lying close enough to the terminal ends of the insula-' tion to practically prevent the creation of a difference of potential between the lead wires inwardly of the point of application of the clip, the clip being indented from one of its free edges inwardly to thereby con s'titute a depressed rib which forcibly engages the bare portions of the lead-in wires and serves the double function of retaining the clip in place and of cleaning said lead-in wires when the clip is stripped longitudinally therefroma.

In testimony whereof he afiixes his signature.

HARRY L. GRANT. 

